The present disclosure relates to a trip button mechanism of an external handle for a circuit breaker.
A circuit breaker may be disposed in a cabinet such as a switchboard cabinet. In this case, an externally operable handle may be attached to the outside of the cabinet to open or close the circuit breaker.
Hereinafter, a related-art trip button mechanism of an externally operable handle for a circuit breaker will be described with reference to the accompanying drawings.
FIG. 1 is a perspective view illustrating a circuit breaker (molded case circuit breaker) for three-phase alternating circuit according to the related art; FIG. 2 is a perspective view illustrating an externally operable handle assembly according to the related art; FIG. 3 is a perspective view illustrating an assembled state of the externally operable handle assembly according to the related art; FIG. 4 is a plan view illustrating the assembled state of the externally operable handle assembly according to the related art; FIG. 5 is a perspective view illustrating an assembly of a pushing plate, an elastic member, and a trip button that is assembled to an outer casing of the externally operable handle assembly according to the related art; FIG. 6 is a perspective view illustrating an assembled structure of the trip button of the externally operable handle according to the related art; FIG. 7 is an exploded perspective view for explaining a method for assembling the pushing plate, the elastic member, and the trip button according to the related art; and FIG. 8 is an enlarged view illustrating the pushing plate and a fitting protrusion according to the related art.
First, referring to FIG. 1, a circuit breaker 10 includes a casing 10a and a cover 10b. The casing 10a has a polyhedral shape with an opened side. Components of the circuit breaker 10 are disposed in the casing 10a. The cover 10b closes the opened side of the casing 10a. 
A manipulation handle 12 is disposed on the cover 10b for opening or closing a circuit. The manipulation handle 12 can be manually manipulated. A circuit breaker trip button 11 is disposed on a side of the cover 10b. The circuit breaker trip button 11 is provided for forcibly tripping the circuit breaker 10. A pair of coupling screw holes 10b-1 is provided at each longitudinal end side of the cover 10b for coupling an externally operable handle assembly 20 (described later) to the cover 10b. 
The externally operable handle assembly 20 includes an outer casing 23, an externally operable handle 22, and an externally operable trip button 30. The outer casing 23 forms the exterior of the externally operable handle assembly 20. The externally operable handle 22 is rotatably attached to a side of the outer casing 23. The externally operable trip button 30 is disposed in a side of the outer casing 23 in a manner such that the externally operable handle assembly 20 can be pushed. For example, the externally operable handle 22 may be connected to the manipulation handle 12 (refer to FIG. 1) through an interlocking device (not shown).
Referring to FIGS. 5 to 8, the externally operable trip button 30 may be connected to the circuit breaker trip button 11 (refer to FIG. 1) through components (described later). The circuit breaker 10 can be forcibly tripped from the outside of a cabinet such as a switchboard cabinet by using the externally operable trip button 30.
A pair of screw connection extensions 24 is provided on each longitudinal end surface of the outer casing 23. The screw connection extensions 24 protrude from both end surfaces of the outer casing 23 for coupling the outer casing 23 to the circuit breaker 10.
Referring to FIGS. 3 and 4, the outer casing 23 is fixed to the cover 10b by coupling screws to the screw connection extensions 24. The outer casing 23 is disposed in the switchboard cabinet (not shown) in a state where the externally operable handle 22 is exposed to the outside of the switchboard cabinet.
Hereinafter, a structure, an assembling method, and functions of the trip button mechanism of the externally operable handle 22 for the circuit breaker 10 will be described in more detail with reference to the accompanying drawings.
Referring to FIG. 7, the trip button mechanism of the externally operable handle 22 includes a button support 25, the externally operable trip button 30, a pushing plate 40, and an elastic member 50.
The button support 25 extends downward from the top surface of the outer casing 23. The pushing plate 40, the elastic member 50, and the externally operable trip button 30 are disposed in the button support 25. For this, the button support 25 includes: a cylindrical hole extension portion 26 having a circular cross section and extending downward from the top surface of the outer casing 23; and a slit extension portion 27 extending downward from the cylindrical hole extension portion 26. The slit extension portion 27 is narrower than the cylindrical hole extension portion 26 so that the externally operable trip button 30 cannot pass through the slit extension portion 27 but the pushing plate 40 can pass through the slit extension portion 27.
Referring to FIG. 6, the externally operable trip button 30 has an approximately cylindrical shape. A cross-shaped connection groove 31 is formed in the bottom surface of the externally operable trip button 30 for connection with the pushing plate 40.
Referring again to FIGS. 7 and 8, the pushing plate 40 may be formed of a thin plate insertable in the slit extension portion 27 of the button support 25. The pushing plate 40 includes an upper vertical plate portion 41, a middle oblique plate portion 42, and a lower hook portion 43.
The upper vertical plate portion 41 is inserted through the slit extension portion 27. A fitting protrusion 44 is provided on the upper end of the upper vertical plate portion 41. The fitting protrusion 44 is insertable in the connection groove 31 of the externally operable trip button 30. The middle oblique plate portion 42 extends from the lower end of the upper vertical plate portion 41 at a predetermined angle. The lower hook portion 43 extends downward from the lower end of the middle oblique plate portion 42. The circuit breaker trip button 11 is substantially manipulated by the lower hook portion 43. The elastic member 50 is disposed in the cylindrical hole extension portion 26. For example, the elastic member 50 may be a coil spring.
A method for assembling the trip button mechanism of the externally operable handle 22 for the circuit breaker 10 will now be described according to the related art.
First, the elastic member 50 is inserted in the cylindrical hole extension portion 26 extending downward from the top surface of the outer casing 23. Next, the externally operable trip button 30 is inserted down to the cylindrical hole extension portion 26. Next, the pushing plate 40 is moved upward to the slit extension portion 27 to insert the upper vertical plate portion 41 in the slit extension portion 27.
Then, the upper vertical plate portion 41 is inserted in the connection groove 31. In this way, the pushing plate 40, the elastic member 50, and the externally operable trip button 30 are assembled.
An operation of the trip button mechanism of the externally operable handle 22 for the circuit breaker 10 will now be described according to the related art.
In the related art, a user may push the externally operable trip button 30 to forcibly trip the circuit breaker 10 disposed in the switch cabinet by using the trip button mechanism of the externally operable handle 22. Then, the externally operable trip button 30 is moved downward against the resilience of the elastic member 50. As the externally operable trip button 30 is moved downward, the pushing plate 40 connected to the externally operable trip button 30 is also moved downward. Therefore, the lower hook portion 43 presses the circuit breaker trip button 11. Then, an internal opening/closing mechanism (not shown) of the circuit breaker 10 is switched to a trip position for interrupting a circuit.
However, as described above, the related-art trip button mechanism of the externally operable handle 22 for the circuit breaker 10 has the following limitations.
In the related art, when the trip button mechanism is assembled or used, the pushing plate 40 and the externally operable trip button 30 may be separated due to the resilience of the elastic member 50 disposed between the pushing plate 40 and the externally operable trip button 30.
Moreover, the externally operable handle 22 is constituted by many components such as the button support 25, the externally operable trip button 30, the pushing plate 40, and the elastic member 50. This may increase manufacturing costs and decrease assembling efficiency.